Time tunnel problems...

[Schrecken_Licht]

I'm trying to make a time tunnel, but I have been having a few problems.  Basically what I have is a motor assembly that I have attached a mirror to, but I'm unsure what angle the mirror needs to be at to get the effect.  

I know the mirror needs to be tilted a little (from horizontal), and I've tried a couple of angles, maybe a 30 degree tilt, and then about half of that.  The first time I got more or less of a liquid sky effect with a little curvature - not what I want, of course.  The second time, I did get a narrower shape but not a circle - what I'm getting is a tear-drop shape instead of a round tunnel... :-?  I get a shape like this when I hit the spinning mirror with a laser (excuse the sloppy photoshopping -it's a thin line of course and not a solid shape):

I don't want a tear-drop shaped tunnel; I want a perfectly round one.

This is how my mirror is set now (as seen from the side view, the mirror being represented by the top line):

What am I doing wrong and why am I not getting a perfect circle?

 

[kernelpanic]

Schrecken_Licht,

I couldn't view your pics. But I can tell you that-

1. You want the mirror to 'wobble' just a little bit. You need only a few degrees off of perpendicular to the axis of spin of the motor.

2. For the time tunnel to be round(ish) you'll want to keep the plane of the mirror roughly 45 degrees to the path of the beam. Also, you'll need to remember the beam becomes oval when the surface you are projecting onto is not roughly perpendicular to the path of the beam.

Get your pictures fixed and it'll be easier to help you...

cheers,
kernel
panic

 

[Schrecken_Licht]

Try these links:
http://onfinite.com/libraries/1415528/d4a.jpg
http://onfinite.com/libraries/1415592/5ea.jpg

You should be able to see them now.

 

[kernelpanic]

Try these links:
http://onfinite.com/libraries/1415528/d4a.jpg
http://onfinite.com/libraries/1415592/5ea.jpg

You should be able to see them now.

Nope. (Browsing from work. Infosec blocks that host...)

cheers,
kp

 

[Cyparagon]

The degree of divergence will be double what the degree of the mirror is with respect to the motor. Any more than 10 degrees is too much, as you'll make more of a disk of light rather than a tunnel.

The shape is possibly caused by excessive motor rattling. If you already have the motor secured, the mirror is likely not secured.

 

[thesk8nmidget]

a good thing to do is just put the mirror on as flat as you can... you wont get it perfect and it will be slightly angled... more than enough for a tunnel. then shine away

 

[Schrecken_Licht]

Ah-HA! Finally got it working! I got a good angle this time - very slight, even though my tunnel is a bit more of a funnel....but that's good for what I'm trying to do.  At least I now know how to adjust the mirror to change the width of the tunnel.  And it's perfectly round....

So, that lady down the street thinks she's got the coolest display going for Halloween night - not any more!  I'll have to post pics of my set-up when I get it all finished.  Thanks everyone for your help.

 

[thesk8nmidget]

good to see you got it all working